The increased use of small portable computers, tablet devices, and smartphones to playback movies, videos, high quality audio, as well as to support audio-intensive applications such as games, simulators, Audio/Visual content production, and so on. Because of their small size and deployment in portable devices that are often used while being held or not firmly affixed to a solid surface (e.g., desk or table), the speakers and drivers are often subject to relatively significant amounts of vibration and external movement. Because rare earth magnets are employed which are considerably smaller and lighter than conventional ceramic types, the magnet experiences increased mobility and becomes a source of vibration transmitted throughout the entire device body if attached mechanically. These effects can produce distortion that compromises the quality of the output audio. Stray vibrations have been found to be a particular problem on small mobile devices such as tablets, laptops and mobile phones because various components vibrate audibly. This effect translates directly to electroacoustic distortion when audio content is played through the speakers of the device. The tuning process is also affected by vibrations as the system is deliberately turned down to avoid buzzing sounds. A system less susceptible to buzzing distortions due to effective vibration control can be tuned to be louder and encompass a wider range of frequencies.
Certain motion canceling designs have been developed to minimize distortion in multi-driver speakers. For example, push-pull opposing drivers can be wired in-phase to cancel driver motion or out-of-phase to cancel harmonic distortion. Such designs, however, are limited to large speakers, such as subwoofers, which have drivers on the order of 12 to 18 inches, or similar. Such large speakers are obviously impractical for small, portable computers and playback devices.
What is needed, therefore, is an audio transducer design that minimizes the effects of distortion caused by vibration and movement of the device in which they are mounted.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.